Answer:
1. <--> A.
2. <--> C.
3. <--> D
4. <--> B.
explanation: i know my science!
The harmonic frequency of a musical instrument is the minimum frequency at which a string that is fixed at both ends in the instrument may vibrate. The harmonic frequency is known as the first harmonic. Each subsequent harmonic has a frequency equal to:
n*f, where n is the number of the harmonic and f is the harmonic frequency. Therefore, the harmonic frequency may be calculated using:
f = 100 / 2
f = 50 Hz
Answer:

Explanation:
1. Find the equation of eht maximal friction force:
The maximal friction force is given by the equation
, where μs is the static friction coefficient, m is the car´s mass and g is the gravitational force.
2. Replace values in the equation to find the answer:


To solve this problem we will use the concepts related to power, defined as the amount of energy applied over a period of time.
The energy in this case is the accumulated in the form of potential energy, over a period of time. Thus we will have that the mathematical expression of the power can be expressed as

Here,
E = Energy
t = time
As the energy is equal to the potential Energy we have tat

The weight (mg) of the man is 700N, the height (h) is 8m and the time is 10s, then:


Therefore the correct answer is A.